Princess Diana’s younger brother, Earl Spencer, will close the museum featuring artifacts from his sister’s life next year, and hand over the contents to her sons, Princes William and Harry, according to the Telegraph.

Diana’s will apparently stated that her belongings were to be “looked after” by Lord Spencer until both of her sons turned 30, at which point the contents would be transferred into their position, the Telegraph reported. Prince Harry turns 30 next year.

A spokesperson for Spencer confirmed to the Telegraph that “It will close worldwide in August 2014.”

The Telegraph suggested that the collection, which includes Diana’s wedding dress, family jewels, pictures, letters and home movies, might go on display at Kensington Palace, where she lived until her death in August 1997.

The Duke and Duchess of Cambridge are scheduled to move into their apartments at the palace after the birth of their first child later this year.

Spencer’s spokersperson said the exhibition at Althorp “has as been admired by thousands of people around the world, and has been a wonderfully tasteful celebration of the late Diana, Princess of Wale’s life and achievements – particularly her charitable works and her glamour,” the Telegraph reported.

Princess Diana’s final resting place is said to be on an island in the center of the “Round Oval” lake on Althorp’s grounds, Maclean’s noted. Between July and early September, guests are allowed to visit the shrine near the island. They are not allowed to set foot on the island itself.